/**
 * #      903
 * 名称   DI 序列的有效排列
 * 链接   https://leetcode-cn.com/problems/valid-permutations-for-di-sequence
 * 题解   [35](https://leetcode-cn.com/problems/valid-permutations-for-di-sequence/solution)
 * 通过率 52.3%
 * 难道   困难
 */

